[JVM_IR] Optimize properties delegated to const val

We can omit `get` call to delegated property and inline
constant value directly. If we are not going to
do that, we can get a runtime exception because
all usages of const property will be inlined and the property
itself will be dropped.

#KT-63567 Fixed
#KT-63580 Fixed

compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/JvmIrLowerUtils.kt

@@ -13,6 +13,7 @@ import org.jetbrains.kotlin.ir.declarations.IrProperty
 import org.jetbrains.kotlin.ir.declarations.IrSimpleFunction
 import org.jetbrains.kotlin.ir.expressions.*
 import org.jetbrains.kotlin.ir.util.getPackageFragment
+import org.jetbrains.kotlin.ir.util.shallowCopyOrNull
 import org.jetbrains.kotlin.ir.util.statements
 
 internal val IrSimpleFunction.returnsResultOfStdlibCall: Boolean
@@ -68,3 +69,14 @@ internal fun IrProperty.getSingletonOrConstantForOptimizableDelegatedProperty():
 fun IrProperty.isJvmOptimizableDelegate(): Boolean =
     isDelegated && !isFakeOverride && backingField != null && // fast path
             (getPropertyReferenceForOptimizableDelegatedProperty() != null || getSingletonOrConstantForOptimizableDelegatedProperty() != null)
+
+internal val IrMemberAccessExpression<*>.constInitializer: IrExpression?
+    get() {
+        if (this !is IrPropertyReference) return null
+        val constPropertyField = if (field == null) {
+            symbol.owner.takeIf { it.isConst }?.backingField
+        } else {
+            field!!.owner.takeIf { it.isFinal && it.isStatic }
+        }
+        return constPropertyField?.initializer?.expression?.shallowCopyOrNull()
+    }

compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/PropertyReferenceDelegationLowering.kt

@@ -41,9 +41,14 @@ private class PropertyReferenceDelegationLowering(val context: JvmBackendContext
 }
 
 private class PropertyReferenceDelegationTransformer(val context: JvmBackendContext) : IrElementTransformerVoid() {
-    private fun IrSimpleFunction.accessorBody(delegate: IrPropertyReference, receiverFieldOrExpression: IrStatement?) =
+    private fun IrSimpleFunction.accessorBody(delegate: IrPropertyReference, receiverFieldOrExpression: IrStatement?): IrBody =
         context.createIrBuilder(symbol, startOffset, endOffset).run {
             val value = valueParameters.singleOrNull()?.let(::irGet)
+            val isGetter = value == null
+            if (isGetter) {
+                delegate.constInitializer?.let { return@run irExprBody(it) }
+            }
+
             var boundReceiver = when (receiverFieldOrExpression) {
                 null -> null
                 is IrField -> irGetField(dispatchReceiverParameter?.let(::irGet), receiverFieldOrExpression)
@@ -54,7 +59,7 @@ private class PropertyReferenceDelegationTransformer(val context: JvmBackendCont
             val unboundReceiver = extensionReceiverParameter ?: dispatchReceiverParameter
             val field = delegate.field?.owner
             val access = if (field == null) {
-                val accessor = if (value == null) delegate.getter!! else delegate.setter!!
+                val accessor = if (isGetter) delegate.getter!! else delegate.setter!!
                 irCall(accessor).apply {
                     // This has the same assumptions about receivers as `PropertyReferenceLowering.propertyReferenceKindFor`:
                     // only one receiver can be bound, and if the property has both, the extension receiver cannot be bound.
@@ -72,7 +77,7 @@ private class PropertyReferenceDelegationTransformer(val context: JvmBackendCont
                 }
             } else {
                 val receiver = if (field.isStatic) null else boundReceiver ?: irGet(unboundReceiver!!)
-                if (value == null) irGetField(receiver, field) else irSetField(receiver, field, value)
+                if (isGetter) irGetField(receiver, field) else irSetField(receiver, field, value!!)
             }
             irExprBody(access)
         }

compiler/ir/backend.jvm/lower/src/org/jetbrains/kotlin/backend/jvm/lower/PropertyReferenceLowering.kt

@@ -67,17 +67,6 @@ internal class PropertyReferenceLowering(val context: JvmBackendContext) : IrEle
     private val IrMemberAccessExpression<*>.field: IrFieldSymbol?
         get() = (this as? IrPropertyReference)?.field
 
-    private val IrMemberAccessExpression<*>.constInitializer: IrExpression?
-        get() {
-            if (this !is IrPropertyReference) return null
-            val constPropertyField = if (field == null) {
-                symbol.owner.takeIf { it.isConst }?.backingField
-            } else {
-                field!!.owner.takeIf { it.isFinal && it.isStatic }
-            }
-            return constPropertyField?.initializer?.expression?.shallowCopyOrNull()
-        }
-
     private val arrayItemGetter =
         context.ir.symbols.array.owner.functions.single { it.name.asString() == "get" }